Final answer:
Rolling from the right side-lying to supine position involves the action of the left internal oblique and the right external oblique, which facilitate rotation and stabilization of the trunk.
Step-by-step explanation:
When rolling from the right side-lying to supine position, the muscles involved are the left and right obliques. Specifically, the action is completed by the left internal oblique and the right external oblique. These muscles work in a coordinated fashion to rotate the trunk, allowing the body to transition smoothly from lying on one side to lying on the back (supine position).
The left internal oblique contracts, pulling the torso toward the centerline of the body, while the right external oblique contracts to assist the rotation and stabilize the trunk during the motion. It's important to note that control and stability during such transitions involve several muscle groups working together, but the obliques play a key role in rotating and stabilizing the trunk.